On Fri, 26 Jul 2024 19:11:10 -0400 Johannes Weiner <hannes@xxxxxxxxxxx> wrote:
> On Fri, Jul 26, 2024 at 08:31:10PM +0000, Roman Gushchin wrote:
> > When a page_counter structure is initialized, there is no need to
> > use an atomic set operation to initialize the usage counter because
> > at this point the structure is not visible to anybody else.
> > ATOMIC_LONG_INIT() is what should be used in such cases.
> >
> > Signed-off-by: Roman Gushchin <roman.gushchin@xxxxxxxxx>
> > ---
> > include/linux/page_counter.h | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/include/linux/page_counter.h b/include/linux/page_counter.h
> > index cf837d0f8ed1..5da11392b382 100644
> > --- a/include/linux/page_counter.h
> > +++ b/include/linux/page_counter.h
> > @@ -53,7 +53,7 @@ static inline void page_counter_init(struct page_counter *counter,
> > struct page_counter *parent,
> > bool protection_support)
> > {
> > - atomic_long_set(&counter->usage, 0);
> > + counter->usage = (atomic_long_t)ATOMIC_LONG_INIT(0);
>
> Pretty cool that ATOMIC_LONG_INIT() return value needs a cast to
> atomic_long_t! ^_^
That's because this wicked patch passed in an `int'.
counter->usage = ATOMIC_LONG_INIT((atomic_long_t)0);
